As is known, handheld printers afford mobile convenience to users. Unlike their immobile or stationary counterparts, however, users determine the path of a given swath of printing. In some instances, this includes random movement over a substrate. In others, it includes back-and-forth movement attempting to simulate a stationary printer.
A common problem with handheld printers is poor alignment between adjacent swaths of print because position of the print element is often less accurate than with other types of printer. Alignment errors usually result in noticeable defects in the print. The most common print defects are called “print banding” and include both dark bands and white bands at the boundary between swaths where ink drops at the edge of a swath are printed too close or too far from drops in the adjacent print swath. Another category of print banding is a directional effect similar to the banded appearance of mowed glass when adjacent swaths are cut in different directions. These print banding defects may appear with other serial printers, but the defects can be minimized by printing a dithered image in multiple passes over the paper. With a handprinter, print banding is a problem because alignment errors are more likely, and requiring multiple passes is an unaccepted demand on the operator.
Another common defect with handprinting is a gap or void in the print where the operator fails to pass the print element over that portion of the page. If detected, the operator can repair the void by moving the print element back over that area so the missing content can be printed. With a handprinter, positional errors accumulate during the page, so voids that are not repaired promptly may have significant print banding where the area printed in repair is misaligned with the adjacent areas.
Accordingly, there exists a need in the art for robust, multi-directional and random printing handheld printers having improved print quality. Naturally, any improvements should further contemplate good engineering practices, such as relative inexpensiveness, stability, low complexity, ease of manufacturing, etc.